Apparatus for making substantially forged articles such as tank tread connectors

ABSTRACT

A billet (10) is pressed with a first blocking punch (36, 38). Thereafter, the billet is rotated approximately 90°. A second punch (50) is pressed against the billet while a split ring die assembly (58) substantially surrounds the billet and constrains outward flow of the steel. The split ring die assembly includes projecting regions (64, 66) matingly received in recesses (14, 16) created by the first blocking punch. A finishing punch (90, 92) is pressed through the billet to complete formation of openings (94, 96). Preferably, a trimmer (100) removes any flashing from the finished billet.

This is a continuation of co-pending application Ser. No. 064,320, filedon June 18, 1987, U.S. Pat. No. 4,848,129.

BACKGROUND OF THE INVENTION

This invention pertains to the art of forming metal articles. Theinvention is particularly applicable in forging tank tread connectorswhich have generally perpendicular forged passages. It is to beappreciated, however, that the invention has broader applications informing other small articles that encounter these same difficulties inmanufacturing.

Conventional methods of forging articles such as tank tread connectorshave been unable to forge the openings required for pin connectionsbetween associated connectors. Previously, articles of this type wereforged to form openings or passages in but one direction. Thereafter,expensive and time-consuming cold machining was required to remove thematerial to create perpendicular and intersecting openings. This problemwas magnified due to the large numbers of connectors that may be formedunder such a conventional method.

Examples of articles and forming articles of this type are shown in U.S.Pat. Nos. 4,294,101 issued Oct. 13, 1981 to Diemer, et al.; 4,425,779issued Jan. 17, 1984 to Diemer, et al.; 4,463,637 issued Aug. 7, 1984 toDelio, et al.; and 4,559,804 issued Dec. 24, 1985 to Delio, et al. Noneof these patents shows minimizing the final machining by pressing abillet along perpendicular directions to substantially formperpendicular openings.

Still other disadvantages result from machining away the excess steelfrom the prior art rough forgings. Cold working of the metal does notenhance or facilitate the strength of the final formed part. The metalhardening inherent in forging operations is absent in other methods ofmanufacturing the articles. Therefore, if more of each articles could beforged, not only are there resultant savings in time and expense but,the forged article has improved strength characteristics.

The present invention contemplates both a method and apparatus formaking substantially forged articles that overcome the above-referencedproblems and others.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a method offorming a substantially forged article. The billet is pressed in a firstdie stroke so that it assumes a predetermined configuration. The billetis then rotated approximately 90° and pressed again in a second diestroke. Thereafter, a finishing punch is pressed through the billet.

According to a preferred method, a pair of split ring die halves areprovided which substantially surround the billet in the second diestroke operation. The split ring die halves are formed with associatedprotrusions and recesses for mating receipt with the first die strokeconfiguration of the billet. Thereafter, the billet is trimmed,preferably simultaneously with the finishing punch pressing step. In asubsequent machining operation, a second opening is completed throughthe recess formed.

In accordance with another aspect of the invention, an apparatus isprovided for substantially forging an article. First and second coactingdie assemblies define die cavities in which a billet is pressed into afirst configuration. A split ring die has recesses and protrusions whichmatingly receive the first configuration billet after it is rotated 90°.A blocking punch is disposed perpendicular to the split ring die fordisplacing the billet. A finishing punch assembly presses through thebillet.

A primary advantage of the present invention is that the article can beheat treated and then machined.

Another advantage of the present invention resides in the substantialcost savings resulting from forging the articles substantially to size.

Still another advantage is found in the stronger article that resultsfrom grain flow around the forged openings.

Yet another advantage is realized in the saving of steel since thearticle is closer to completion once it leaves the die assembly.

Still other advantages and benefits of the invention will becomeapparent to those skilled in the art upon a reading and understanding ofthe following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take form in certain parts and arrangements of partsor various steps in arrangements of steps. The specification andaccompanying drawings are only for purposes of describing a preferredembodiment and are not to be construed as limiting the invention.

FIG. 1 is a top view of an article formed in accordance with the presentinvention;

FIG. 2 is a cross-sectional view generally along the lines 2--2 of FIG.1;

FIG. 3 is a partial cross-sectional view also generally along the lines2--2 of FIG. 1 after additional machining steps and insertion of awedge-shaped fastener;

FIG. 4 is a sectional view through a die assembly and billet generallyillustrating the initial forging steps of the present invention;

FIG. 5 is a sectional view after the billet forged in the die of FIG. 4has been rotated through approximately 90° and received within a splitring cavity;

FIG. 6 is a sectional view generally along the lines 6--6 of FIG. 5 andparticularly illustrating the tongs and split ring assembly.

FIG. 7 is a sectional view through the die assembly particularlyillustrating the finishing and trimming steps of the subject invention;

FIG. 8 is a perspective view of an alternative embodiment of the subjectinvention;

FIG. 9 is a top view of yet another alternate embodiment of the subjectinvention; and,

FIG. 10 is a cross-sectional view generally along the lines 10--10 ofFIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT AND METHOD

The FIGURES show a substantially forged article A that undergoes aseries of pressing steps in a die assembly B. The forged articleillustrated in FIGS. 1 and 2 results in a substantial cost savings overarticles made in a conventional manner which require more extensivemachining. The forged article A is illustrated as a tank treadconnector, although it will be understood by those of ordinary skill inthe art that still other articles embracing the general principles andconcepts of this forged article may be made in a similar manner.

With particular reference to FIG. 4, a billet 10 is pressed in a firstblocking assembly to assume a generally oval peripheral configuration12. In the initial blocking step, a first set of oppositely disposedrecesses 14, 16 are formed in the billet while it is still hot andsusceptible to forging operations. The first blocking die assemblyincludes a first or upper die 24 and a second or lower die 26.Typically, the lower die is stationary and the upper die 24 securelymounted to a ram (not shown) for relative movement toward and away fromthe lower die. The upper die includes a generally arcuate or concavecavity 28 that substantially matingly receives the billet 10. Likewise,the lower die includes a generally arcuate or concave cavity 30 thatfaces the upper die cavity and also matingly receives the billet. Anupper blocking punch 36 extends downward from the upper die into thecavities 28 and 30. Likewise, a lower blocking punch 38 extends upwardfrom the lower die and into the die cavity 30.

The billet is positioned between the upper and lower dies and, whilestill hot, the upper die is moved relative to the lower die and theblocking punches form the associated recesses 14, 16 in the billet. Theblocking punches 36, 38 extend substantially, but not completely,through the billet along a first plane or axis. It is particularly notedthat this blocking punch pressing operation does not form a flashingthat often results from similar pressing operations. Instead the arcuatecavities of the dies provide a smooth outer surface to the billet. Theupper die is then moved away from the lower die and an ejector 40,typically fluid pressure actuated, assists in removal of the billet fromthe cavities. The billet now has a first predetermined configurationresulting from the first blocking punch pressing operation; namely, agenerally elliptical peripheral surface with the oppositely disposedrecesses 14, 16 between generally planar, parallel front and rear faces.

Turning now to FIGS. 5 and 6, the billet 10 has been rotated throughapproximately 90° relative to its position in FIG. 4. The die assemblynow includes a second blocking punch 50 comprised of first and secondgenerally frusto-conical punch members 52, 54. Once again, the blockingpunches are dimensioned to extend substantially through the billet alonga second plane or axis perpendicular to that of the first die operationplane or axis. It is preferable that the blocking punches not extendcompletely through the billet. A tong assembly 56 is operativelyconnected to a split ring die assembly 58. The split ring die assemblyincludes first and second half portions 60, 62 that completely encompassthe billet. More particularly, the half portion 60 includes a projection64 having the general configuration of blocking punch 36 which generallyfills recess 14. Similarly, a projection 66 of the other half portion 62has a configuration that closely resembles that of blocking punch 38 andgenerally fills recess 16. The remainder of a cavity 68 defined by thesplit ring die assembly closely receives the generally ellipticalperipheral billet surface for reasons which will become more apparentbelow.

As illustrated in FIGS. 5 and 6, the punch members 52, 54 are pressedinto engagement with the billet along a generally perpendicular to acommon central axis of recesses 14, 16. The punch members are positionedclose to the recess 14 but sufficiently spaced therefrom so as not tointersect therewith. Preferably interconnecting portions or webs 78, 80are defined between recesses or cavities 82, 84 formed by the punchmembers 52, 54 and the recesses 14, 16. As particularly shown in FIGS. 2and 3, these interconnecting webs are removed by machining after theforging operation in order to interconnect recess 14 with the cavities82, 84.

With reference now to FIG. 7, a pair of finishing punches 90, 92 arealigned with the cavities 82, 84. The punches are pressed downwardthrough the remainder of the billet 18 to enlarge the cavities 82, 84into openings 94, 96. It is these cylindrical openings which areseparated from the recesses 14, 16 and later interconnected when thewebs 78, 80 are removed through a machining operation.

With continuing reference to FIG. 7, lower end portions of the finishingpunches 90, 92 each have a stellite peripheral edge to facilitateformation of the openings 94, 96. Likewise, a surrounding trimmer 100has an inner peripheral stellite cutting edge to remove any flashingalong the outer periphery of the forged billet. Preferably, the trimmerand finishing punches are simultaneously moved downward relative to thebillet to remove any exterior flashing that is formed during the secondblocking die operation.

In the trimmer and finishing punches described above, the billet 10 isseated on a nest 102 which, in turn, is received in a nest holder 104 ondie set shoe 106. The punches extend through a forging stripper 108 andmove axially relative thereto during reciprocating motion of the ram(not shown). The upper trimmers and punches are fixed to a drum 116which is secured to a die set punch holder 118. Lastly, a banjo 120 isfastened to the forging stripper 108 to assist in removal of the punchesfrom the billet.

In operation, the billet is removed from the die assembly after thesecond die stroke shown in FIG. 5. The billet is disposed on the nest asshown in FIG. 7 and the punch and trimmer advanced downward to removethe flashing and form the openings 94, 96. The return or upward strokeof the punches would lift the billet off the nest if a means forseparating the billet from the punches were not provided. According tothe preferred embodiment, elongated rods 122 extend from the banjo andengage a stop 124 to limit the upward movement of the billet. Morespecifically, the banjo engages nuts 126 at the upper end of the rod andnuts 128 at the lower end engage stop 124. The banjo is prevented fromfurther upward movement which is transferred to the forging stripper108. The forging stripper, in turn, limits upward movement of thebillet. The punches continue moving upward relative to the billet tocomplete the third die stroke operation.

Referring again to FIG. 3, a fastening member 132 has a wedge-shapedportion 134 at one end and a threaded region 136 at the other end. Oncethe machining steps that remove the interconnecting webs have beencompleted, the wedge-shaped portion 134 is matingly received in therecess 14 that has been enlarged by machining. The threaded regioncooperates with a nut 138 in the recess 16 which has been trued bymachining to facilitate connection of the tank tread connector 18. Sincethe connection of the tank tread connectors is generally conventionaland forms no part of the subject invention, no further discussion isdeemed necessary.

As referenced above, prior art methods of forming the openings 94, 96resorted to machining after the forging operation. This, of course,resulted in considerable expense and machining time whereas the subjectinvention provides a forged billet after the finish punch arrangementthat is substantially complete.

FIG. 8 illustrates an alternative embodiment in which the second punch50 is formed as an elongated unitary member having a generally FIG. 8cross-sectional configuration. A unitary punch rather than the separatepunches previously described eliminates even more machining. Insubstantially all other respects, the generally forged billet A'undergoes the same steps as described above.

Turning now to the alternate embodiment of FIGS. 9 and 10, the forgedarticle A" differs from the embodiment of FIGS. 1-3 in the formation ofrecess 16". As best shown in FIG. 9, opposite end regions 132, 134 openthe recess 16" to the peripheral edge of the connector. These cutoutregions 132, 134 permit and facilitate access with a wrench or othertool into the recess 16".

The invention has been described with reference to the preferredembodiment. Obviously, modifications or alterations will occur to othersupon a reading and understanding of the specification. It is intended toinclude all such modifications and alterations insofar as they comewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An apparatus for forming a substantially forgedarticle comprising:a first die assembly having a first die cavityreceiving a first blocking punch therein, and a second die cavityreceiving a second blocking punch, said first and second die cavitiesdisposed in facing relation to receive an associated billet therein andcoact to press said billet into a first predetermined configuration inwhich the blocking punches form opposed, non-interconnecting first andsecond recesses in the billet; means for rotating said billetapproximately 90 degrees; a second die assembly having a first diecavity receiving third and fourth blocking punches therein, and a seconddie cavity, said first and second die cavities disposed in facingrelation and further including projections extending substantiallyperpendicular to the third blocking punch for receipt in the recessesformed in the first die assembly, said third and fourth blocking punchesextending a predetermined dimension substantially less than the billetto form third and fourth recesses on opposite sides of and perpendicularto the first and second recesses; and a third die assembly havingcooperating first and second die cavities for receiving the billettherein from the second die assembly, the third die assembly includingfirst and second finishing punches that extend completely through thethird and fourth recesses.
 2. The apparatus as defined in claim 1further comprising a trimmer operative associated with said finishingpunch assembly for removing flashing resulting from said second blockingpunch.
 3. The apparatus as defined in claim 1 wherein the projectionsare defined on a split ring die assembly including a split ring.